Fixed lowest/highest visible x-index (Closes #785, closes #794)
Fixed lowest/highest visible x-index (Closes #785, closes #794)

Shannon-s-Dreamland/Charts,icecrystal23/ios-charts,convergeeducacao/Charts,danielgindi/Charts,danielallsopp/Charts,Shannon-s-Dreamland/Charts,LiveHappier/Charts,jesseXu/Charts,ConcepterDev/ios-charts,aelam/Charts,liuxuan30/Charts,liuxuan30/ios-charts,gjpc/ios-charts,summerlove57/ios-charts,jesseXu/Charts,liuxuan30/ios-charts,MAARK/Charts,summerlove57/ios-charts,franqueli/ios-charts,LiveHappier/Charts,MAARK/Charts,ConcepterDev/ios-charts,franqueli/ios-charts,LiveHappier/Charts,Eflet/Charts,boluomeng/Charts,jjatie/Charts,franqueli/ios-charts,Eflet/Charts,dtrauger/Charts,FreddyZeng/Charts,FreddyZeng/Charts,boluomeng/Charts,convergeeducacao/Charts,MAARK/Charts,ConcepterDev/ios-charts,aelam/Charts,liuxuan30/ios-charts,aelam/Charts,dtrauger/Charts,danielgindi/Charts,MAARK/Charts,jjatie/Charts,Eflet/Charts,jum/Charts,jjatie/Charts,hanquochan/Charts,boluomeng/Charts,ekohe/ios-charts,hanquochan/Charts,hanquochan/Charts,shujucn/ios-charts,SBGMobile/Charts,liuxuan30/Charts,icecrystal23/ios-charts,jum/Charts,ekohe/ios-charts,boluomeng/Charts,duanhjlt/ios-charts,liuxuan30/Charts,dtrauger/Charts,FreddyZeng/Charts,summerlove57/ios-charts,jum/Charts,SBGMobile/Charts,danielgindi/Charts,danielgindi/ios-charts,danielgindi/Charts,duanhjlt/ios-charts,danielgindi/ios-charts,Eflet/Charts,danielgindi/ios-charts,jesseXu/Charts,SBGMobile/Charts,dtrauger/Charts,jjatie/Charts,liuxuan30/Charts,danielgindi/ios-charts,danielallsopp/Charts,shujucn/ios-charts,SereivoanYong/Charts,icecrystal23/ios-charts,SereivoanYong/Charts,jum/Charts,SereivoanYong/Charts,gjpc/ios-charts,duanhjlt/ios-charts,icecrystal23/ios-charts,FreddyZeng/Charts,liuxuan30/ios-charts,ekohe/ios-charts,hanquochan/Charts,shujucn/ios-charts,gjpc/ios-charts